Introduction to zinc knowledge, how is metal zinc synthesized?
Zinc is a chemical element. Its chemical symbol is Zn, and its atomic number is 30. It is located in the fourth period and group ⅡB of the periodic table of chemical elements. Zinc is a light gray transition metal and the fourth “common” metal. In modern industry, zinc is irreplaceable in battery manufacturing and is a very important metal. In addition, zinc is also one of the essential trace elements for the human body and plays an extremely important role.
Zinc is difficult to burn in the air and emits a strong white light in oxygen. There is a layer of zinc oxide on the surface of zinc, which emits white smoke when it burns. The main component of the white smoke is zinc oxide, which not only blocks the burning of zinc, but also reflects the color of the flame to form a pale light. Zinc is easily soluble in acid and can easily replace gold, silver, copper, etc. from the solution. The oxide film of zinc has a high melting point, but the melting point of metallic zinc is very low. So heating the zinc flakes on an alcohol lamp will melt and soften the zinc flakes, but does not fall down, precisely because of the effect of the oxide film. Zinc is mainly used in steel, metallurgy, machinery, electrical, chemical, light industry, military and pharmaceutical fields.
1. Vacuum down 360g of metallic zinc and slowly add it to 3340ml of 15% sulfuric acid solution, and heat to 70°C for reaction. When the H2 no longer overflows, dilute with 1200ml of water to prepare the zinc sulfate solution, take out 50ml, and use the rest for later use. 4g of sodium carbonate was added to 50ml of the diluted solution, and the precipitated zinc carbonate precipitate was washed three times with water (300ml each time) for use. Dissolve 7.5 g of ferrous sulfate heptahydrate in 500 ml of water, acidify with 1 ml of superior grade pure sulfuric acid, heat, and add 30% hydrogen peroxide dropwise to convert all Fe2+ ions in the solution to Fe3+ ions. Add the prepared iron sulfate solution to the above-mentioned spare zinc sulfate solution, and add the prepared zinc carbonate precipitate with stirring, then heat to 30-40ºC under rapid stirring, and let it stand. After the solution is clear, filter it. [ Removal of Fe(OH)3 precipitates with As, P, Sb and other impurities]. The filtrate is electrolyzed and the PH value is adjusted to make the Congo red slightly blue. During electrolysis, use premium grade pure or zinc flakes as the cathode, industrial zinc as the anode, the distance between the two electrodes is 2-3cm, the voltage between the two electrodes is 6V, and the current density depends on the temperature of the electrolyte. After 200g of zinc is precipitated, the electrolyte must be treated again with iron sulfate and zinc carbonate according to the above method.
2. Preparation of zinc is prepared by smelting zinc blende ZnS as the main raw material. Industrially, ZnS is usually oxidized and calcined into an oxide with good reactivity. Then use thermal reduction method and electrolysis method to prepare zinc. The charge made of zinc roasting block and coal powder is put into the zinc smelting furnace at 1300~1350°C for reaction, the metal zinc vapor generated by the reduction reaction is passed into the zinc condenser through the conduit, and the metal zinc is captured. The metal zinc obtained by this method has a relatively high impurity content. To obtain purer zinc, vacuum distillation is required.
3. Dissolve the zinc oxide in the calcined material with sulfuric acid, remove iron by oxidation, remove cobalt, copper, nickel and other impurities with zinc powder, then place it in an electrolytic cell with lead as the anode and aluminum plate as the cathode. During electrolysis, metallic zinc is deposited on the aluminum plate and peeled off to become a product. The purity of metallic zinc produced by electrolysis can reach 99.99%.
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Reference source: Internet
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Post time: Sep-06-2021